After the dialog, Darion initiates combat but instead of taking out his flamer, he just runs away. This seems really odd to me. Is it because his model doesnt have the animations for using a big gun, so he cant actually use the flamer? That seems like a HUGE oversight...
I'm assuming you probably have the same version Restoration Project as me considering the date-stamp on your post. I just faced him, and I didn't have that problem at all. But I still killed him just as easily because his two combat-armor guards kept shooting him in the back, and of course just coming from, can't remember the name, I had made an effort to get the best burst weapons I could find. I had the G11 and the P90c. So, I stayed at a distance when I saw him and walked away to get behind a wall.
Darion ran right up to me, got shot in the back twice, with some pretty good damage, and I unloaded a burst weapon on him. The rest were fairly easy because I think I'm overpowered right now. I saved my money, and did about 2 caravans, and got myself to that place I can't remember the name using a caravan, and I was able to obtain a p90c, and now p90c's seem to be pretty common. That's probably due to the YAAM that comes with RP or perhaps the RP. I'm sure, just like with Fallout, I'm going to be overpowered just long enough for it to totally screw up my game.
I'll get used to this ease at which I'm killing my enemies, and then suddenly big weapons, energy weapons, mutants, high-resistance foes will start treating me like a ragdoll, and I'm not going to know what to do about it. That's what happened in Fallout. I did the same thing, saved money, got myself overpowered for my current level, then suddenly the much harder enemies came along, and I got stuck somewhere without enough stimpaks or ammo to do anything, nor to get back to civilization to build my stocks back up again. But I've got a car in this one, so maybe that won't happen again.
Oh, I forgot, when I walked into the room with Darion, I got taken down to about half health in the immediate turn, so I panicked and took a Psycho shot, a few stimpaks, and ran to hide behind the wall so that they would come up to me, and I could burst them. But after that, I guess due to how quickly I killed Darion, thus the flamer was taken out of the battle, I didn't even drop below 80 HP at level 15. So, in hindsight, I probably wasted that Psycho, but it wasn't really wasted because I found it most useful for the 2nd floor, which I hadn't eliminated yet because I wanted to use my limited stimpaks on Darion, and typically in games like this, targets are on the deepest levels of their dungeons.
Well, Darion was my chosen target because I haven't yet gotten any quest to actually get rid of him. After buying my weapons and combat armor, I immediately went to that area Darian is at because you know, my people are dying because they put their faith in a piece technology that in reality probably would never ever work after this much time. I wanted to tell them, "hello, there's a reason that some native Americans and even lots of tribal-like cultures were literally nomads." Some Native Americans followed the buffalo literally because otherwise, they would be in the exact same predicament.
Okay, I need to stop editing this thing before it becomes a book.
Anyway, good luck. If it doesn't keep happening with other enemies, then maybe you simply stumbled upon a rare action that Darian takes under certain circumstances of the player character. This game is so jam-packed with random occurrences that it's likely that many many of them haven't even yet been discovered. Darian running off might have simply been a rare probability based on your character's stats that simply no one has yet discovered.